Coaxial connector mounting means

ABSTRACT

Coaxial connector mounting means comprises mounting block means connectable together to connect coaxial connector means floatably mounted in the mounting block means.

United States Patent Ziegler, Jr.

- 51 Oct. 24, 1972 I54] COAXIAL CONNECTOR MOUNTING MEANS [72] Inventor:George William Ziegler, .lr., Carlisle, Pa. 731 Assignee: AMPIncorporated, Harrisburg, Pa. 221 Filed: Sept. 18,1970 21 Appl.No.:73,652

Related US. Application Data {62] Division of Ser. No. 732,447, May 27,1968,

Pat. No. 3,566,334.

[52] US. Cl. ..339/64 M [51] Int. Cl. ..H01r 13/62 [58] Field of Search..339/64, 177, 91, 184

[56] References Cited UNITED STATES PATENTS 5/1963 Takes et al ..339/l77 R 3,235,834 2/1966 OKeefe et al. ..339/l77 -R 3,471,825 10/1969 Huber..339/l77 R FOREIGN PATENTS OR APPLICATIONS 773,012 12/1957 GreatBritain ..339/91 R Primary Examiner-Joseph H. McGlynn Attorney-Curtis,Morris and Safford, Marshall M.

l-lolcombe, William Hintze, William J. Keating,

Frederick W. Raring, John P. Hopkins, Adrian J. La

Rue and Jay L. Seitchik [57] ABSTRACT Coaxial connector mounting meanscomprises mounting block means connectable together to connect coaxialconnector means floatably mounted in the mounting block means.

7 17 Drawing Figures PATENTEDnm 24 m2 SHEET 6 OF 9 COAXIAL CONNECTORMOUNTING MEANS This is a divisional application of application Ser. No.732,447, filed May 27, 1968, now US. Pat. No. 3,566,334.

This invention relates to mounting means and more particularly tomounting means for floatably mounting coaxial connector means therein.

Mounting coaxial connectors in mounting means so that they can be matedis conventional practice in the field of coaxial connectors. Suchconventional mounting means does not provide for the misalignmentbetween mating connectors as well as for inherent tolerances whichimpedes mating between the connectorsand improperly mated connectorsdetracts from the operational characteristics of the connectors,

It is a primary object of the present invention to provide a coaxialconnector mounting means which compensates for misalignment betweenmating connectors and inherent tolerances therebetween.

Another object of the invention is the provision of floatably mountingall of the coaxial connectors in coaxial connector mounting means sothat proper matin g engagement between the connectors is effected.

A further object of the invention is to provide coaxial connectormounting means wherein at least some of the coaxial connectors arespringably mounted thereon to compensate for all errors includingmanufacturing tolerances.

An additional object of the invention is the provision of floatablymounting the mounting'blocks of coaxial connector mounting means inhousing means so that compensation for tolerances is overcometherebetween.

A still further object of the invention is to provide cantilever springmeans for the coaxial connector mounting means which have projectionmeans thereon for engagementwith the coaxial connectors, the projectionmeans providing more uniform spring action during deflection thereof.

Still an additional object of the invention is the provision of guideblock means floatably mounted on one mounting block means.

Still a further object of the invention is to provide mounting means forconnecting individual connectors together whether they be sexed orsexless.

Other objects and attainments of the present invention will becomeapparent to those skilled in the art upon a reading of the followingdetailed description when taken in conjunction with the drawings inwhich there are shown and described illustrative embodiments of theinvention; it is to be understood, however, that these embodiments arenot intended to be ex haustive nor limiting of the invention but aregiven for purposes of illustration in order that others skilled in theart may fully understand the invention and the principles thereof andthe manner of applying it in practical use so that they may modify it invarious forms, each may be best suited to the conditions of a particularuse.

In the drawings:

FIG. 1 is a perspective view of coaxial connectors connected togethervia the coaxial connector mounting means;

FIG. 2 is a view taken along lines 2-2 of FIG. 1;

FIG. 3 is an exploded perspective view of the mounting means of FIGS. 1and 2;

FIG. 4 is a perspective view partially exploded of a coaxial connectormounting means for a single sexed coaxial connector;

FIG. 5 is a longitudinal cross-sectional view of FIG.

FIG. 6 is a view taken along lines 6-6 of FIG. 5;

FIG. 7 is a longitudinal cross-sectional view of an alternativeembodiment of FIGS. 4 through 6 illustrating connection means for asexless connector;

FIG. 8 is an exploded perspective view partially in section of analternative embodiment of the coaxial connector mounting means;

FIG. 9 is an exploded perspective view of a further embodiment of thecoaxial connector means;

FIG. 10 is a cross-sectional view of FIG. 9 with elements and each partof the housing means in an assembled condition;

FIG. 11 is a view taken along lines 11-11 of FIG. 10; 1

FIG. 12 is a view taken along lines 12-12 of FIG. 9;

FIG. 13 is a view taken along lines 13-13 of FIG. 12;

FIG. 14 is a partially sectioned view illustrating a hood mounted on oneof the housing means of the embodi'ment of FIGS. 9 through 13;

FIG. 15 is an exploded and perspective view of an ad ditional embodimentof the coaxial connector;

FIG. 16 is a longitudinal cross-sectional view of a jack sleeve having ajack connector secured in position therein; and

FIG. 17 is a view taken along lines 17-17 of FIG. 16 illustrating thepolarization between the jack sleeve and jack connector.

Turning now to the drawings and more particularly to FIGS. 1 through 3,a coaxial connector mounting means CM is illustrated which is preferablyused for mounting jack connectors 1 and plug connectors 2 of the typedisclosed in US. Pat. No. 3,245,027 for terminating the connectors onsemi-rigid coaxial cables 3 via ferrules 4. Connectors 1 and 2 areprovided, with annular grooves 5 and mateable center contacts 6 and 7,center contacts 6b and d, jack center contact and center contacts 7b andd, plug center contact. Beveled surfaces 8 and 9 are providedrespectively on the jack counter 1 and plug connector 2 and similarbeveled surfaces are provided on the mateable sections of centercontacts 6 and 7. Sealing O-rings 10 are provided on plug connectors 2adjacent shoulders 11 thereof.

Jack connectors 1 and plug connectors 2 are respectively mounted inopenings 12 extending through a mounting block 13. Of course, a mixtureof jack and plug connectors can be mounted in each of one of blocks 13.Retaining plate 14 is mounted on a surface of each of blocks 13 viascrews 15 through holes 16 in plates 14 and threaded holes 17 in blocks13. Holes 16 are large enough to permit limited freedom of movement inthe X-Y plane about screws 15 and screws 15 are provided withprojections 15a which permits the screws to bottom in threaded holes 17and not hold retaining plates 14 in snug engagement with the surfaces ofblocks 13 so that retaining plates 14 are movable in limited directionin the 2 direction. Retaining plates 14 are provided with U-shapedrecesses 18 which mate with annular grooves 5 in three connectors ineach of blocks.

A spring retaining plate 19 is also mounted on the surfaces of mountingblocks 13 that retaining plates 14 are mounted via screws 20 throughholes 21 in plate 19 and threaded holes 22 in mounting block 13 therebysnugly mounting plate 19 thereto. Plate 19 is provided with a leg 23having an arcuate recess 24 for engagement with the groove in the centerconnector and cantilever springs 25 are provided with arcuate areas 26for engagement with annular grooves 5 of the other connectors therebyspringably securing these connectors in position in' blocks 13. Blocks13 are secured together via jack screws 27 which are screwed intoposition in one of blocks 13 via threaded hole 28 and mateable with acorresponding threaded hole 28 in the other mounting block 13 therebysecuring the blocks together. Plates l4 and 19 are provided with holes29 through which jack screws freely pass.

The connectors held in position via floatable retaining plate 14 definethree points of a plane at the outer ends of the connectors so thatconnection between the eorresponding mateable connectors can beestablished.

Limited axial movement is provided by the difference between the widthof grooves 5 on the connectors and the thickness of the retaining plate14 which is threadably mounted along the X-Y plane and motion restrictedin Z direction by screws 15 on the mounting block. Spring retainingplate 19 is rigidly mounted on the mounting block via screws 20 andcantilever springs 25 permit restricted motion in the Z direction plusrestricted movement along the XY plane due to the spacing betweenarcuate areas 26 of each pair of cantilever springs 25. Cantileversprings 25 extend slightly above the plane of the retaining plate 14 ini order to pick up all of the errors or manufacturing tolerances suchas: lack of planarity of block surfaces, lack of planarity of bothsurfaces of both retaining plates and distance between the pressureedges of grooves 5 of the plug and plug fitting nose and between thepressure edges of grooves 5 of the jack fittings and jack fitting matingplane or shoulders.

The retaining plates allow unrestricted motion of the connectors in theX-Y plane and limited motion in the Z direction, the openings in theblock in which the connectors are retained by the retaining plate limitthe movement. in the X-Y plane. Each surface of each mounting block 13can be used to mount the retaining plates thereon. Beveled surfaces orchamfers 8 on the internal surfaces at the nose of jack fittings 1provide a target for the beveled surfaces of chamfers 9 of the plugconnectors and the chamfers of the jack connectors capture and compressthe sealing rings against shoulders 11. The chamfers of the plug andjack connectors have to be fully engaged before mating starts betweenthe plug center contact and the entry end of the jack center contactspring fingers. The chamfers at the plug and jack connector noses haveto be at a minimum of siZe which is equal to or greater than the sum ofthe true position and tolerance errors of the holes in the blocks, thefitting diameter tolerances plus the space are nominal plus any set onthose plug con- .nectors that may have spring finger settings.

Mounting blocks 13 are preferably of the thickness of one and one-halftimes the diameter of openings 12 in order to minimize the deviation ofconnector axes relative to the Z direction which is normal to the X-Yvnectors have to have spring fingers secured via retaining plates 14 onthe mounting blocks depending upon the application. Also, a combinationmay be used when only three or fewer connectors require butt joints andits concomitant improved performance as compared to wiping contacts inan array of connectors, the remainder of which are of less criticalapplication .(wiped contacts) wherein the wipe type contacts are held bya retaining plate that is of proper dimension so as to position three orless connectors to positively provide butt contact by another plate orportion of the same plate that advances into Z direction the three (orfewer) connectors positively by an amount equal to or exceeding the sumof the Z direction tolerances.

FIGS. 4 through 6 illustrate coaxial connector mounting means CMaincluding a sleeve 30 provided with an external threaded section 31 andsleeve 32 having an internal threaded section 33. Sleeves 30 and 32 aredisposed on a jack connector 1 and a plug connector 2 and each of thesesleeves is provided with diametrical slots 34 for receiving therein legsof U-shaped retaining members 35 which also mate with annular grooves 5in connectors l and 2 so that when sleeves 30 and 32 in position onconnectors 1 and 2 and retaining members 35 in position in slots 34 andgrooves 5 sleeves 30 and 32 are threadably connected via sections 31 and33 to move the connectors into engagement with each other and alsocenter contact 6 and 7 in engagement with each other. Connector mountingmeans CMa therefore defines mounting means for connection and holdingtogether a single jack connector and plug connector. Diamet'rical flatsurfaces 36 .are provided in each of sleeves 30 and 32 to enable awrench to be engaged thereon to tighten sleeves 30 and 32. Sleeves 30and 32 can be a single sleeve provided with slots 34 and retainingmembers 35 can be V- shaped spring members to drive the connectormembers together in the single sleeve.

FIG. 7 shows plug connectors 2 butted together at their noses andinserted within sleeve 37 which extends between shoulders 11 so thatO-rings 10 are engaged by the internal beveled surfaces thereof. Centercontact 38 is disposed in a dielectric bushing, sections 40 of centercontact 38 electrically engageable with the center conductors of coaxialcables 3. Sleeves 30 and 32 and retaining members 35 maintaining plugconnec- 1 block 41 in position on a mounting panel 46 and openings 47 inwhich connectors 42 are disposed. Openings 47 are provided withenlargments 48 in which coil springs 49 are disposed surroundingconnectors 42, coil springs 49 extending between the inner ends ofenlargements 48 and shoulders 50 on connectors 42. Snap rings 51 matewith grooves 52 and connectors 42 to limit movement of connectors 42 inopenings 47 while coil springs 49 and shoulders 50 limit movement of theconnectors in openings 47 in the other direction. Coil springs 49 permitconnectors 42 to be floatably movable in an axial direction when beingmated with corresponding jack connectors 44 to compensate for anytolerance variation.

Connectors 44 are mounted in openings 53 and block 43 which communicatewith a slot 54 in the front of block 43 thereby accommodating the nosesof connectors 44 and flanges 54 which limit movement of the connectorsin one direction in openings 53. Nuts 55 threadablyengage threadedsections 56 of connectors 44 as a preferable means of securing theseconnectors in openings 53.

Guide pins 57 are mounted in openings 58 (only one being shown) in block41. Snap rings 59 are disposed in grooves 60 at one end of guide pins 57to limit movement thereof in one direction. Openings 58 are providedwith enlargements 61 wherein coil springs 62 are disposed surroundingsections of guide pins 57 and disposed between flanges 63 of guide pins57 and the inner ends of enlargements 61 so that the guide pins arefloatably mounted in block 41. Guide pins 57 mate with holes 64 in block43 when blocks 41 and 43 are mated together to connect jack connectors42 with plug connectors 44. Thus, guide pins 57 are spring loaded viacoil springs 62 on mounting block 41 to compensate for tolerances of themounting blocks 41 and 43 and mounting means 45 for mounting ontomounting member 46. Connectors 42 and 44 are preferably connected tosemi-rigid coaxial cable but can be connected to flexible coaxial cableif desired.

FIGS. 12 through 14 illustrate coaxial connector mounting means CMdwhich is a further embodiment of the invention. Mounting blocks 65 and66 carry jack connectors 1 and plug connectors 2 respectively inopenings 67 thereof. Block 65 is mounted in a jack housing 68 and block66 is mounted in a plug housing 69 against inwardly-directed flanges 70thereof to limit movement of blocks 65 and 66 in the Z direction. Blocks65 and 66 are held in position in housings 68 and 69 by means of setscrews 71 threadably disposed in the sides of blocks 65 and 66 andloosely mounted in oversize holes 72 located in opposing sides ofhousings 68 and 69 to provide movement of mounting blocks 65 and 66 inthe X-Y plane and in the Z direction within housings v68 and 69. Jackhousing 68 is mateable with plug housing 69 to effect the innerconnection between connectors 1 and 2 and the housings are held inengagement by means of jack screws 73 disposed in a flange 74 on housing68 and threaded openings 75 and flange 76 of housing 69. A gasket 77 isdisposed within housing 68 and is engageable by the flange front end ofhousing 69 to provide a seal and also to apply pressure for spring clipmeans if such are used in place of jack screws 73.

Spring retaining plates are provided with cantilever springs 79 whichare diametrically disposed in annular grooves 5 of connectors 1 and 2 inthe same manner as spring retaining plate 19 of FIGS. 1 through 3.Spring retaining plates 78 are movably mounted on mounting block 65 and66 via screws 80 which are threadably mounted in threaded holes 81 andwhich are provided with shoulders 82 which mate with openings 83 inretaining plate 78, shoulders 82 abutting against mounting blocks 65 and66 and openings 83 being large enough to permit retaining plate 78 to befloatably mounted thereon. The outer ends of spring 79 are chamfered foreasy engagement with the grooves of the connectors.-

Cantilever springs 79 at each mounting position along the springretaining plate 78 define cantilever beams supported at both ends butfree to move and each cantilever spring includes a projection 84engageable by the pressure edge of a groove 5 of a connector to effectthe spring action, the projections of spring 79 for each connector beingcoincident with the axis of the connector along a diameter thereof andengageable thereby so that the pressure surface of the groove 5 of theconnector engages the projections and not the cantilever beams duringspring action thereof thereby providing uniform spring action duringdeflection. The engagement of the connector on the projections 84 tendsto make the torsion of the cantilever beams more nearly uniform duringdeflection thereof. Also, projections 84 tend to minimize the effect ofthe float of the fitting within the holes of the block and the float ofthe retaining plate 78 about its nominal position.

A guide block 85 is floatably mounted on mounting block 66 by means ofscrews 86 disposed in holes 87 of guide block 85 and extend throughholes 88 in plate 78 and into threadable engagement with threaded holes89 in block 66. Screws 87 are provided with shoulders 90 which abutagainst block 66 and openings 88 are large enough to permit retainingplate 78 to be floatably mounted thereon. Also holes 87 are providedwith reduced sections 87a permitting guide block 85 to be floatablymounted in the X-Y plane as well as in the Z direction over thefloatably mounted spring retaining plate.

Guide block 85 is provided with openings 91 extend ing therethrough andin which the outer ends of plug connectors 2 are disposed as illustratedin FIG. 10. The entrances to openings 91 are chamfered. The floatabilityof guide block 85 in its mounting arrangement on mounting block 66 issuch that there is no restricted motion of the plug connectors 2 withinthe mounting block. The chamfered entrances of openings 91 are of suchmagnitude as to pick up the float in the X-Y plane of the blocks withinthe housings and the float of the plug housing and the jack housing aswell as the mismatch of the connectors themselves. The guide blockprojects spring finger contacts of plug connectors as well as joint typeconnectors.

Instead of external jack screws in the housings, internal jack screwsbetween mounting blocks directly can be used thereby enabling the use ofspring retaining member plates which are required for butt contactconnectors together with housings and hoods.

Turning now to FIG. 14, jack housing 68 is disposed in an opening 92 ofa mounting panel 93 and screws 94 extend through flange 74 and inthreadable engagement with mounting panel 93 to secure housing 68 inposition thereon. A hood 95 is secured onto flange 76 of housing 69 viascrews 96 with a gasket 97 disposed therebetween. Coaxial cables 3extend through respective threadedopenings 98 in hood 95 and nuts 99 arethreadably mounted in openings 98 thereby compressing seal means 100,such as for example, plastic or rubber washers, into sealing engagementaround cables 3 thereby providing a sealed environment. Rubber grommetscan be used in place of nuts 99 and seal means 100 with the grommetssnugly engaging the cables to provide the sealing arrangement.

Turning now to FIGS. through 17, coaxial connector mounting means CM isillustrated which includes mounting blocks 101 and 102 which areprovided with jack sleeves 103 and plug sleeves 104 which are mateablewith each other as well as jack connectors 1 and plug connectors 2 whichare mateable with respect to one another. Blocks 101 and 102 are securedin frames 105 and 106 via roll pins 107 to provide stiffly-flexiblemounting between the mounting frames and blocks. The mounting frames actas cantilever beams to pick up accumulated tolerances enabling use oflatch arms 108 which are secured to frame 105 and are spring-biased byspring means 109.

Jack sleeves 103 and plug sleeves 104 along with jack connectors 1 andplug connectors 2 are mounted in blocks 101 and 102 by means ofspring-retaining plates 78 to provide the floatability therefore asdiscussed hereinabove. In the case of jack sleeves 103 and plug sleeves104, a bar 110 is secured onto the rear surfaces of blocks 101 and 102and they are disposed in slots 111 formed in sleeves 103 and 104 tomaintain sleeves 103and 104 in a promptly oriented position so thatconnectors 112 of the type disclosed in US. Pat. No. 3,144,292 can beproperly oriented in sleeves 103 and 104 via projection 113 on carryingmember 114 mating with slot !115 disposed in sleeves 103 and 104.Securing member 114 is provided with lances 116 in engagement with ashoulder 117 within the sleeves 103 and 104 and forward projections 118on securing member 114 engage shoulder 119 in sleeves 103 and 104 tolimit movement of the connector in one direction within the sleeves.Projections 120 on securing member 114 are stablilizing projections tostabilize connectors 112 in sleeves 103 and 104. Sealing means 121 issealingly compressed onto flexible coaxial cable means 122 via nuts 123threadably disposed in threaded openings 124 in sleeves 103 and 104.Other types of connectors than that disclosed in US. Pat. No. 3,144,292,can, of course, be used.

While the mounting blocks in the above described embodiment are madefrom metal, it is to be understood, where needed, the mounting blockscan be made of a suitable thermosetting plastic and this would be truein the case of flexible cables having dielectric sheathing around theouter conductive means.

It will, therefore, be appreciated that the aforementioned and otherdesirable objects have been achieved; however, it should be emphasizedthat the particular embodiments of the invention, which are shown anddescribed herein, are intended as merely illustrative and not asrestrictive of the invention.

The invention is claimed in accordance with the following:

1. A coaxial connector mounting means for mounting mateable coaxialconnectors thereonto, which comprises:

a. mounting block means having openings extending therethrough forreceiving coaxial connectors therein;

b. retaining plate means floatably mounted on said mounting block means;

c. cantilever spring means provided by said retaining plate means forsecuring said coaxial connectors on said mounting block means, saidcantilever spring means including projection means engageable by saidcoaxial connectors; and

d. securing means provided by said mounting block means for securingsaid mounting block means together with mateable ones of the coaxialconnector means in mating arrangement.

2. A coaxial connector mounting means according to claim 1 wherein saidmounting block means are mounted in a stiffly-flexible manner in framemeans which act as cantilever beams to pick up accumulated tolerances.

3. A coaxial connector mounting means according to claim 1 wherein saidsecuring means are spring-biased latch arms.

4. A coaxial connector mounting means for mounting coaxial connectormeans thereonto, which comprises:

a. mounting block means having opening therethrough for receiving thecoaxial connector means therein,

b. retaining plate means floatably mounted on said mounting block means,said retaining plate means including spring retaining means havingcantilever beams for engagement with areas of said coaxial connectormeans to retain the coaxial connector means in said openings and topermit movement of said coaxial connector means in an X-Y plane and in aZ direction, said spring retaining means supported at both ends on themounting block means.

5. A coaxial connector mounting means according to claim 4 wherein saidcantilever beams include projection means for engagement with the areasof the coaxial connector means. V

6., A coaxial connector mounting means for mounting coaxial connectorsthereonto comprising mounting block means having openings extendingtherethrough for receiving first coaxial connectors in some of saidopenings, sleeve means disposed in the remainder of said openings forreceiving therein second coaxial connectors, means provided by saidsleeve means and on said second coaxial connectors for polarizing saidsecond coaxial connectors in said sleeve means, retaining plate meansmounted on said mounting block means and including retaining meansengageable with areas of said first coaxial connectors and said sleevemeans for retaining the first coaxial connectors and said sleeve meansin said openings, and means provided by said sleeve means and saidmounting block means polarizing said sleeve means in position on saidmounting block means.

7. A coaxial connector mounting means according to claim 6 whereinspring-biased latch means are provided on one of said mounting blockmeans for latching engagement with another of said mounting block meansto hold the mounting block means in a latched condigagement.

1. A coaxial connector mounting means for mounting mateable coaxialconnectors thereonto, which comprises: a. mounting block means havingopenings extending therethrough for receiving coaxial connectorstherein; b. retaining plate means floatably mounted on said mountingblock means; c. cantilever spring means provided by said retaining platemeans for securing said coaxial connectors on said mounting block means,said cantilever spring means including projection means engageable bysaid coaxial connectors; and d. securing means provided by said mountingblock means for securing said mounting block means together withmateable ones of the coaxial connector means in mating arrangement.
 2. Acoaxial connector mounting means according to claim 1 wherein saidmounting block means are mounted in a stiffly-flexible manner in framemeans which act as cantilever beams to pick up accumulated tolerances.3. A coaxial connector mounting means according to claim 1 wherein saidsecuring means are spring-biased latch arms.
 4. A coaxial connectormounting means for mounting coaxial connector means thereonto, whichcomprises: a. mounting block means having opening therethrough forreceiving the coaxial connector means therein, b. retaining plate meansfloatably mounted on said mounting block means, said retaining platemeans including spring retaining means having cantilever beams forengagement with areas of said coaxial connector means to retain thecoaxial connector means in said openings and to permit movement of saidcoaxial connector means in an X-Y plane and in a Z direction, saidspring retaining means supported at both ends on the mounting blockmeans.
 5. A coaxial connector mounting means according to claim 4wherein said cantilever beams include projection means for engagementwith the areas of the coaxial connector means.
 6. A coaxial connectormounting means for mounting coaxial connectors thereonto comprisingmounting block means having openings extending therethrough forreceiving first coaxial connectors in some of said openings, sleevemeans disposed in the remainder of said openings for receiving thereinsecond coaxial connectors, means provided by said sleeve means and onsaid second coaxial connectors for polarizing said second coaxialconnectors in said sleeve means, retaining plate means mounted on saidmounting block means and including retaining means engageable with areasof said first coaxial connectors and said sleeve means for retaining thefirst coaxial connectors and said sleeve means in said openings, andmeans provided by said sleeve means and said mounting block meanspolarizing said sleeve means in position on said mounting block means.7. A coaxial connector mounting means according to claim 6 whereinspring-biased latch means are provided on one of said mounting blockmeans for latching engagement with another of said mounting block meansto hold the mounting block means in a latched condition and the coaxialconnectors thereon in mating engagement.